Mutations Fill in the Blanks 1. A mutation arises mainly by DNA copy errors. 2. The term “mutation’ was coined by Hugo de Vries. 3. Substitution of a purine base by a pyrimidine base or vice versa is known as transverse mutation. 4.Transistion mutation involves replacement of a purine base by another purine base or a pyrimidine base by another pyrimidine base. 5. The ability of a molecule to exist in more than one form is called allomorphism. 6. A chemical resembling a base in its structure is called base analogue. 7. Guanine is deaminated to xanthine. 8. Mutations are the primary source of genetic variation. 9.Acquired mutations are not transmitted to future generations. 10. CIB method of detecting mutations in Drosophila was discovered by H. J Muller. 11. Nitrous acid causes changes in the DNA bases by replacing the amino group with a keto group. 12. The short-legged lamb discovered by Seth Wright germinal mutation. is an example of dominant 13. The gene of sickle cell anaemia is a missence gene. 14. Tautomers are produced by the rear rearrangements of protons (H) and electrons in molecules. 15. The mutagenic effect of ultraviolet rays was discovered by Edgar Altenburg. 16. It was Auerbach and Robson who first reported that mutations can be induced by chemicals. 17. 2-aminopurine can pair with thymine by two hydrogen bonds and with cytosine by 2 hydrogen bonds. 18. Transitions may be produced by tautomerizations. 19. Ochre mutation is the mutation of a sense codon. 20. A single mutation affecting more than one character is called pleiotropic mutations. 21.Hot spots are the favourable sites for mutations. 22. H J Muller received the Nobel Prize for discovering x-ray induced mutations. 23. Enzyme Alkyl transferase catalyses removal of the alkyl group from the base. 24. Attached X chromosome technique for detection of mutation is simple as mutation can be detected in first filial generation. 25. In Salmonella typhimurium, glycine tRNA contains CCCC instead of the triplet CCC in the anticodon position. 26. The effect of a nonsense mutation can be suppressed by nonsense suppression. 27. Mutations occurring under natural conditions are called spontaneous mutations. 28. Deamination of adenine causes formation of hypoxanthine, which pairs with cytosine. 29. Mutations that inactivate genes are called suppressor mutations. 30. Sites containing 5-methylcytosines provide hotspots for spontaneous mutations. 31. The frequency of mutations can be increased by mutagens. 32. Mutation theory of evolution was proposed by Hugo de Vries. 33. Enol state of thymine pairs with guanine. 34. The smallest segment of gene capable of undergoing mutation is called muton. 35. Mutation involving the removal of a gene is known as deletion. 36. Mustard gas as a chemical mutagen was first of all used by Auerbach and Robson. 37. During the course of development, the phenotype changes while the genotype remains relatively constant, except the rare changes called mutations. 38. Homoeosis is the replacement of one body part by a different one. The mutants causing such effects are called homeotic mutants. 39. A large number of cells become affected, if mutation occurs during embryonic development. 40. Single base substitution occurs when DNA replication takes place interphase during of the cell cycle. 41. Sometimes point mutations are reversed by other point mutations. 42. Suppressor mutations can be distinguished from reverse mutation by comparing reversed stock to wild type. 43. In dominant autosomal mutation of an affected heterozygous individual, around 3 quarters of offsprings are expected to show this trait. 44. Photoreactivation is catalysed by the enzyme photolyase. 45. A dietary source of mutagen is heterocylic amines and is a possible cause of cancer. 46. A single individual will carry mutation, if it occurs in sperm cells or egg cells. 47. Genetic mutations are the result of substitutions, insertions and, deletions in the DNA. 48. The first individual showing a mutation is called first-step mutant. 49. A new mutation that was not inherited from either parent is called a de novo mutation. 50. The effects of neutral mutations do not influence the fitness of an individual. 51. An induced mutation variety of wheat is the semi-dwarf variant. 52. The primary mutagenic effect of ultraviolet rays is due to the formation of pyrimidine dimers. 53. Mutation in TP53 gene is responsible for majority of human cancers. 54.Antioxidants destroys mutagens. 55.Beneficial mutations are useful to us.